The present invention relates to fluid couplings, and more particularly to fluid couplings useful for connecting massflow controllers, on-off valves and connecting blocks interposed between these devices in fluid control apparatus for fabricating semiconductors.
Fluid control apparatus for use in fabricating semiconductors comprise controllers, such as massflow controllers for controlling flow rates and pressure regulators for controlling pressure, and on-off valves, etc. in combination with the controllers. The present applicant has already proposed a desirable arrangement wherein a massflow controller is connected to an on-off valve by a suitable connecting block for use in such control apparatus (see JP-A No. 326943/1996). FIG. 6 shows the construction of a fluid coupling disclosed in the proposal.
With reference to FIG. 6, the fluid coupling comprises male and female coupling members 9, 92 having gasket holding annular projections 98, 99 respectively on butting end faces thereof, an annular gasket 93 interposed between the butting end faces of the two coupling members 91, 92, and a retainer 94 holding the outer periphery of the gasket 93 to retain the gasket 93 on the female coupling member 92. Each of the coupling members 91, 92 may be a connecting block, massflow controller body, or block joined to an on-off valve. One of the butting end faces of these coupling members 91, 92 is of the male type, and the other end face is of the female type. A fitting raised portion 95 formed on the butting end face of the male coupling member 91 and projecting axially thereof is fitted in a fitting recessed portion 96 formed in the butting end face of the female coupling member 92, whereby the coupling members 91, 92 are prevented from being displaced from each other radially thereof. A retainer holding cylindrical portion 97 is formed on the butting end face of the female coupling member 92. The retainer 94 holds the cylindrical portion 97, whereby the gasket 93 is retained on the female coupling member 92.
The conventional fluid coupling comprises two kinds of coupling members, i.e., the male type and the female type, so that when to be joined to each other, these members need to be distinguished with respect to the joining direction and therefore require much time and labor for joining. Moreover, when the joining direction is to be reversed, there arises the problem of necessitating other coupling members which are reversed in male-female relationship.
If the difference of being male and female is eliminated, the effect to prevent the axial displacement by fitting is no longer available, and the gasket holding annular projection 98 of the coupling member 91 which is not held by the retainer 94 becomes liable to shift radially relative to the gasket 93. This entails the problem that the projection 98 becomes released from the end face of the gasket 93 to result in impaired fluid tightness.